Cultures Of Unicellular Algae Research Articles

Evaluation the toxic effect of copper ions on the condition indices of benthic diatom Actinocyclus subtilis (W.Gregory) Ralfs 1861 in the experiment

Introduction. Pollution of marine coastal areas lead to the relevance of environmental monitoring including application of biotesting methods based on- the cultures of unicellular algae. Microalgae have different species-specific resistance to pollutants that expands application of different species as bioindicators of marine pollution.
 The aim of the study was to determine the threshold concentration of copper ions (Cu2+) for the survival and increase in the cells number of benthic diatom Actinocyclus subtilis (W.Gregory) Ralfs 1861 (Bacillariophyta) under the wide range of toxicant concentrations during 10-day toxicological experiments.
 Material and methods. The response of strain culture of the benthic diatom A. subtilis to various concentrations of copper sulfate (ranged from 16 to 1024 μg/l in terms of Cu2+ ions) was studied. In accordance with the previously developed protocol, the following indices were evaluated: alterations in the absolute number and proportion (%) of alive cells in the test-culture, as well as the specific growth rate in the number of A. subtilis cells at different concentrations of toxicant. Counting of alive and dead cells was carried out by micrographs taken for 12–15 random viewing fields under Nikon Eclipse inverted light microscope.
 Results. It was found that in the control and at concentration of copper ions 16 μg/l, the increase in the absolute number of cells in culture is described by sigmoid response curve. At the control еhe exponential growth phase occurs on days 5–7 and at concentration of 16 µg/l on days 3–5 of the experiment. The threshold concentration of copper ions (32 μg/l) which is critical for the survival of A. subtilis was determined, which is 3–7 times lower than threshold level for other benthic diatom species. At concentration of 32 µg/l, the phases of acceleration and exponential growth on the abundance curve are absent. The proportion of living cells in the culture decreases to 80% of the control level on day 3 and to 39% by day 10. At Cu2+ concentrations of 64 µg/l and above, sharp inhibition and death of culture is observed as early as 1–3 days. A positive specific growth rate of A. subtilis culture was revealed in the period of 1–5 days at copper concentration of 16 and 
 32 µg/l, and at concentration of 64 µg/l and higher the culture dies off. Negative values of the specific growth rate for all concentrations of the toxicant within the period of 5–10 days were obtained.
 Limitations. By the results of 10-day experiments the effect of 8 concentrations of copper sulfate on the culture of marine benthic diatom A. subtilis was studied. Three replicates in each concentration and exposure time were measured (1350 measurements in total), which is sufficient sampling for statistically reliable determination of the threshold values of copper ion toxicity for given test object.
 Conclusion. Considering the results obtained, the benthic diatom A. subtilis is highly sensitive to copper ions impact and can be recommended as new test-object for toxicology, as well as for application in monitoring of marine water areas subject to technogenic pollution.

Effects of Pure Paraquat Dichloride, “Gramoxone W”, and Formulation Additives on Soil Microbiological Activities: 1. Estimations of soil biomass in laboratory-treated soil

The effects of normal and ten-times normal field rates of paraquat dichloride, “Gramoxone W” and formulation additives on soil microbial biomass in a calcareous loam was examined. Numbers of bacteria, fungi, and actinomycetes, by the dilution agar plate method, showed only slight and transient increases or decreases as a result of treatment. Direct microscopy of soil-agar films showed no severe changes in numbers of soil propagules. It is thought that the small changes in populations, shown by the agar plate method, may be undetectable by direct microscopy. The amount of adenosine triphosphate present in the soil biomass was not severely affected by the treatments. These results were in agreement with the direct microscopy, but not the agar plate count results. The ability of a mixed population of unicellular algae to survive in soil was not severely affected by the three chemicals. There was evidence of a transitory synergistic effect between paraquat ions and formulation additives. In the absence of clay minerals, cultures of unicellular algae were totally inhibited by paraquat ions and numbers were decreased by the high rate of additives. It is concluded that despite the laboratory processing of soils, there is no evidence to suggest that paraquat, “Gramoxone W” or additives severely disrupt the microbial soil biomass. Der Einfluß von Paraquat-Dichlorid, „Gramoxone W“ sowie dessen Formulierungszusätzen au die Biomasse des Bodens wurde in einem kalkhaltigen Lehmboden untersucht. Die applizierten Mengen entsprachen einer normalen sowie einer zehnfachen praxisüblichen Konzentration. Die mit Hilfe der Agar-Platten-Methode ermittelten Bakterien-, Pilz- und Aktinomyzetenzahlen zeigten nur einen geringen und vorübergehenden Anstieg oder Abfall als Ergebnis der Behandlung. Direkt-Mikroskopie von Boden-Agar-Filmen zeigten keine bedeutenden Veränderungen in der Keimzahl des Bodens. Möglicherweise sind die Veränderungen der Population, die mit Hilfe der Agar-Platten-Methode ermittelt wurden, mit der Direkt-Mikroskopie nicht festzustellen. Der in der Biomasse des Bodens vorhandene Gehalt an Adenosin-triphosphat (ATP) wurde durch die Behandlung nicht bedeutend beeinflußt. Während diese Ergebnisse mit den Zahlen der Direkt-Mikroskopie übereinstimmten, fehlte eine solche Übereinstimmung beim Vergleich mit der Agar-Platten -Methode. Die drei Chemikalien beeinflußten die Lebensfähigkeit einer gemischten Population einzelliger Algen im Boden nicht stark. Aber offensichtlich war ein vorübergehender, synergistischer Effekt zwischen Paraquat-Ionen und den Formulierungszusätzen vorhanden. In Abwesenheit von Tonmineralen wurden Kulturen einzelliger Algen durch Paraquat-Ionen vollständig inhibiert, ihre Anzahl wurde durch die hohe Konzentration der Formulierungszusätze vermindert. Aus den vorliegenden Ergebnissen wird geschlossen, daß es trotz der labormäßigen Behandlung der Böden keinen Beweis für die Annahme gibt, daß Paraquat, „Gramoxone W“ oder dessen Formulierungszusätze die mikrobielle Biomasse des Bodens in bedeutendem Umfang stören.

Studies on the growth of some marine unicellular algae under different artificial light sources

Documented evidence of the suitability of various artificial light sources for the culture of unicellular algae is scarce. This paper reports the results of a comparison of the growth rates of 5 species of marine unicellular algae at various light intensities produced by an incandescent filament source or daylight fluorescent tubes. Under light saturating conditions the maximum growth rate achieved by each species was the same under each artificial source. Under sub-optimal intensities, no difference in the growth rates under the 2 sources was detected in the case of Phaeodactylum tricornutum, Chlorella ovalis or Monochrysis lutheri. However, under these conditions both Brachiomonas submarina and Dunaliella primolecta required higher intensities of incident illumination from the fluorescent source than from the incandescent source to maintain a particular relative growth rate.

Experiments on the artificial rearing of the larvae of Pinctada maxima (Jameson) (Lamellibranchia)

Attempts to rear the larvae of P. maxima from the egg up to metamorphosis are described. A simple apparatus for the continuous culture of unicellular algae was developed. Local algae were isolated as possible foods but none of those available promoted rapid larval growth. Maximum gonad development of P. maxima occurs in the period September-March. Attempts to induce spawning in ripe oysters were unsuccessful. Artificial fertilization was accomplished during treatment of stripped gametes with ammonium hydroxide. Large numbers of larvae were produced but mortality was high. Early straight-hinged larvae were approximately 75 by 70 �, and the pediveliger stage was reached when larvae were approximately 130 by 110 �. The fastest rate of growth was recorded when larvae were fed on a mixture of Isochrysis and Monochrysis. A variety of substrata was offered for settlement but metamorphosis was not completed. Further studies are required before the feasibility of commercial rearing can be assessed.

Effect of Filtrates from Cultures of Unicellular Algae on the Growth of Staphylococcus aureus

Effect of Filtrates from Cultures of Unicellular Algae on the Growth of <i>Staphylococcus aureus</i>